Investment compound



PATENT OFFICE.

EDMUND L GBIFFITH, FBBEPORT, ILLINOIS.

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No Drawing.

This invention relates to a new dental investment material or compound.

The principal object of the invention is to provide anew material for dental molding in place of plaster of Paris or silex which are now commonly used and are objectionable because of the time consuming methods that are necessitated in their. use, the present material being capable of being ignited or fired to solidify the molded mass thereof in about a half minutes time whereas about an hours time was otherwise required in the initial setting and subsequent heating of the molds to drive out the moisture therefrom preparatory to pouring.

Another object is toprovide a material for the purpose referred to which may be prepared in a large batch for several fillings instead of having to prepare a separate batch for each job, thus elimmating another material time consuming operation. Any unused portion of a batch instead of being Waste, as was the case with plaster of Paris and silex, can be set aside and may be remoistened sometime later and made plastic and capable of use.

The dental investment compounds at present in use rely upon the use of water to render the same plastic. This introduces a considerable time element in the setting and subsequent heating of the molded mass since it is absolutely necessary that all moisture be driven out before the mold is oured. The setting of the mold usually too from twenty to thirty minutes alone. The subsequent heating to drive out any residual moisture consumed another twenty to thirty minutes. In other words, it took about an hours time to place the mold in readiness for pouring. According to the present inventlon, this waste of time is avoided by providing an investment material which is rendered plastic by a combustible liquid such as alcohol and can be ignited or fired due to the presence of this liquid to take a set, solidify and be relieved of its moisture content all in about half a minutes time with the further assurance after the firing that no objectionable moisture will be left 1n the mold. With the other investment materials, there is no certainty of this without posltlve tests.

In the making of a filling, or rather in the pfeparation of amold for the pouring of a 1mg, a wax model is first produced which is fixed on a sprue in a sprue former. The

Application filed February 4, 1926. Serial No. 86,047.

wax model is then painted with a plaster investment compound which is usually very fine grained and comparatively porous to produce sharp, clear cut margins on the filling eventually produced. The coating is allowed to harden for eight to fifteen minutes, whereupon the sprue former is placed in an investment ring into which the main mass of investment compound to form the mold is flowed surrounding the model. This practice has been commonly followedfor some time. With the use of the investment compounds at present available, as previously stated, the ring had to be left standing for twenty or thirty minutes to allow the mold to take a set. After this, it was possible to drive out the moisture present b the use of a Bunsen flame which also took om twenty to thirty minutes. With the use of my investment material, the composition of which I will set forth shortly, the time for setting and the time for heating are practically eliminated as the mold may be ignited or fired at once and is ready for casting in about ten minutes time.

My investment material preferably consists of the following parts by volume, to wit One-third molding clay, one-third finely or cast under pressure. The asbestos insures .the cohesion of the molded clay, in an obvious manner. It is obvious that any unused portion of a batch of the compound that has been mixed will not take a set as was the case with plaster of Paris or silex. Consequently, it is not wasted but can be used for the next mold. If the alcohol or other combustible moistening has dried out, it is merely necessary to add more to make the material plastic and ready for use. Thus. another important saving in time is ell'octed as well as a saving in material.

While I have described a particular composition which, at the present time, I have selected as a preferred embodiment of my invention, it will, of course, be understood that some variations and departures may be made without sacrificin some of the more important advantages w ich are derived in the use of the material described. It is, 5 therefore, to be understood that the invention is capable of adaptation and modification withmthe spirit and scope of the a'p pended claims.

I claim:

1. A dental investment material moistoned and made plastic with a combustible liquid whereby to be susceptible of ignition to dry and solidify the mass thereof in. a mold.

2. A dental investment material capable of i ition to take a set and form a solid mold ready to be poured.

3. A dental investment com ound comprising a clay material made astic with a 20 readily combustible volatile iquid having substantially the properties of alcohol.

4. A dental investment compound comprising a clay material admixed with an interlacm agent such as fibrous fire-proof materia and made lastic with a readily combustible volatile iiquid having substantially the properties of alcohol.

5. A dental investment compound comprisin a. clay material admixed with a combustib e firin material. 6. A denta investment material which is capable of i nition to simultaneously set solidify, and e relieved of the moisture content thereof. i

7 A dental investment compound consisting of one-third molding clay, one-third fine- 1y ground fire clay, and one-third finely ground asbestos each by volume rendered elastic with a volatile li uid having sub stantially the properties 0 alcohol.

In witness of the foregoing I aflix my signature.

EDMUND L. GRIFFITH.

that some variations and departures may be made without sacrificin some of the more important advantages w ich are derived in the use of the material described. It is, 6 therefore, to be understood that the invention is capable of adaptation and modification withm the spirit and scope of the appended claims.

I claim: 1. A dental investment material moistened and made plastic with a combustible liquid wherebyto be susceptible of ignition to dry and solidify the mass thereof in. a mold. 15 2. A. dental investment material capable of i ition to take a set and form a solid mol ready to be poured.

3. A dental investment com ound comprising a clay material made f) astic with a 0 readily combustible volatilei uid having substantially the properties of a cohol.

4. A dental investment compound comprising a clay material admixed with an interlacm agent such as fibrous fire-proof materia and made lastic with a readily combustible volatile tially the properties of alcohol.

5. A dental investment compound comprisin a clay material admixed with a combustib e firing material.

.7 6. A dental investment material which is EDMUND L. GRIFFITH.

CERTIFICATE OF CORRECTION.

Patent No. 1,658, 437.

Granted February 7, 1928, to

EDMUND L. GRIFFITH.

it is hereby certified that error appears in the theahove numbered patent requiring correction as foilo'ws; claim 6, after the word "set" insert a comma: same page,

printed. specification of line 38,-clain 7, 1

aiter the word "volume" insert the words "arranged to he", and line 39, same claim, for the word "elastic" read "plastic"; and that the aaidLettera Patent should he read with these corrections therein that the same may eonform to the record of the case in the Patent Office.

Siane llll celled this 6th day of March, A. D. 1928.

Seal.

"a Jo Acting Comisa'ioaer of Patents.

quid having substan- CERTIFICATE OF CORRECTION.

Patent No. 1,658,437. Granted February 7, 1 3, 10

EDMUND L. GRIFFITH.

it in hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 32. claim 6, after the word "set" insert a comma; same page, line 38,elaim 7, alter the word "volume" insert the words "arranged to be", and line 39, same claim, for the word "elastic" read "plastic"; and that the said Letters Patent should be read with these corrections therein that the same may eonform to the record of the case in the Patent Office.

Signed and lelled this 6th day of March, A. D. 1928.

M. J. Moore, Acting Conmlaaioner oi Patenta. 

